Small but perfectly formed
I have a total of 4 accounts with TSB, and pass money between them to maximise interest. One is a Vantage account which I've had for years; two are those new Classic Plus accounts which pay the best interest rates around. The fourth is a monthly saver account which neatly mops up any excess cash.
When I sign into TSB online, all the accounts are there on one page so I can simply smooth them all off to take the best advantage of their respective rates. The monthly saver doesn't pay as much interest as the Classic Plus accounts, but has the advantage that you can keep building it and receiving interest on all the money in there.
You can only pay in a maximum of £250 per month, though, hence the juggling. Otherwise, I'd just pay in as much or as little as I could afford each time.
Easy to manage; reasonable and stable interest rate